Following certain injuries, surgery or other medical treatments that affect the mobility of the knee, it is customary for the patient to be prescribed physical therapy. For example after knee operation, scar tissue may form in knee tissue (i.e. arthrofibrosis) and as such, mobility of the knee may suffer. For example, without rehabilitative therapy, a patient who has undergone knee surgery may not be able to walk properly or return to independent daily activities and could potentially suffer from back pain, hip pain, and knee pain.
Normal range of motion of the knee is considered to be 0° of extension and 135° degrees of flexion. For example, 0° of extension may be achieved by a person extending their knee such that their lower leg is parallel with their upper leg. An upper leg of a patient is also known as a thigh, and is defined as the area between a patient's pelvis and knee. For example, the upper leg usually includes the femur. On the other hand, a lower leg of a patient is defined as the part of the leg that lies between the knee and the ankle. The lower leg usually includes the fibula and the tibia. As another example, 135° of flexion can be achieved when a person flexes their lower leg such that an angle subtending their lower leg and their upper leg is 45°. Knee extension describes straightening of the lower leg relative to the upper leg, and knee flexion describes bending the knee such that an angle between the lower leg and the upper leg decreases. Hip extension described straightening the upper leg relative to the spine, and flexion is described as bending the hip joint such that the upper leg to spine angle decreases.
Field of the Invention
The present invention relates to knee range of motion therapy, and more particularly to a knee range of motion therapy device.
Description of the Related Art
Commonly, a physician may prescribe therapeutic exercises to help a patient regain normal knee flexion and extension ranges, otherwise known as range of motion. For example, a therapist may prescribe active range of motion (AROM) exercises, active assisted Range of Motion (AAROM) exercises, passive range of motion (PROM) exercises, and/or progressive resisted exercises (PRE) to help strengthen muscles surrounding the knee and break down scar tissue. AROM is defined as moving a body part without assistance of another. AAROM is defined as moving a body part with the assistance of another. PROM is defined as moving a body part with only the assistance of another. PRE are defined as movement of a body part against or opposing outside resistance.
As an example, to increase range of motion in the knee, a physical therapist may apply passive range of motion therapy. For example, to increase flexion range of the knee, the therapist may manually pull the patient's foot toward the patient's body, increasing a flexion angle of the knee. After a desired flexion is achieved, the therapist may return the patient's foot to the original position to complete a cycle. Such therapy is applied on a frequent basis and maximum extension and flexion angles are measured to quantify progress.
However, such manual methods are inconvenient because either the therapist or the patient has to travel on a frequent basis, possibly for many months. As such, knee therapy via a physical therapist is time-consuming, inefficient and costly.
Efforts may be made to train others, for example, the wife or husband of the patient, to perform these exercises. However, such training efforts have poor results, however, due to lack of patient and caregiver compliance and insufficient training to replicate the skill of a licensed therapist.
Such issues with manual methods have led to development of machines that attempt to reproduce the capabilities of a licensed physical therapist, allowing therapy to be provided without requiring the patient or a therapist to travel and spend time providing therapy. For example, a therapy machine may be provided to a patient so that the patient may engage in therapy by themselves. However, current knee range of motion therapy machines have various problems. Common knee range of motion therapy machines merely apply a translational force to the foot of a patient via a horizontal track system. Other common knee range of motion machines require two separate machines for flexion and extension, respectively.
As such, common knee range of motion machines are not able to rotate a knee of a patient independently from a hip joint of the patient, which may be an issue for patients with hip dysfunction. Further, current range of motion therapy machines place significant translational force on the lower leg of a patient, which applies unnecessary and undesired translational forces on the knee joint. Furthermore, common range of motion therapy machines are not configured to record usage data, which may help track progress or check on patient compliance. Even further, current range of motion therapy machines are not able to concurrently and safely provide the above described active and passive range of motion therapy modalities, because common machines are not able to anatomically match a rotational axes of a patient's leg so that a patient may apply anatomically matched rotational forces, or the machines require an inconvenient hand crank to assist the passive or active motions.
Therefore, there exists a need for a knee range of motion therapy machine or device that can rotate a knee of a patient independently from a hip of the patient, provide both active and passive range of motion therapies and record usage data to track progress and check patient compliance.